Method of expediting the removal of frozen masses



ePf- 17, 963 J. M. LINDBERGH AL 3, 4,1 6

METHOD 0F EXPEDITING T REMOVAL OF FROZEN MASSES Filed March 29. 1961 s sheets sh Sept 17, 1963v J. M. LINDBERGH ETAL .3,104,186

METHOD OF EXPEDITING THE REMOVAL OF FROZEN MASSES Filed March 29, 1961 s sheets-sheet 2 United States Patent O 3,l4,186 METHOD F EXPEDHMG THE-REMVAL 0F FROZEN MASSES t lon M. Lindbergh, San Diego, Calif., and .lames W. Warren, Jr., Salt Lake City, Utah, assigner-s to Explosive Engineering Corporation, San Diego, Calif., a corporation oi California Filed Mar. 29, 1%1, Ser. No. 99,691 Claims. (Cl. 134-17) This invention relates to the art of handling frozen masses, and more particularly to la procedure for effecting the rapid break-up and removal `of dense7 tough, lirozen masses, such as frozen salamanders 'from blast furnaces and open hearth furnaces.

The term salamander is the designation given to the mass of material below the original hearth line of a blast furnace or open hearth furnace, which has replaced or partly replaced the original lining material of the furnace. Genenally it may be constituted of molten iron or a mixture of molten iron and parti-ally solidified burden materials interlaced with lingers of iron. Open hearth furnace bottoms contain fingers or pockets of steel. Since cast iron contains about 4% carbon, it will be readily apparent that a `frozen salamander is very hard and tough and heretofore many problems have been present incident to its removal from the furnace.

Furnaces must be relined from time to time in order to insure eicient operation and to insure satety since the lining is `deteriorating continuously. It would be desirable if a` salamander could be tapped into lad-les while in ya molten state. Attempts have been made to do this in the past. Toft Patent 2,810,634 discloses Ianattempt to minimize the size oi a salamander through steepening the angle of the furnace tap hole and lengthening it prior -to the last cast. However, this method is not always effective :and hence is not in general use. Bottom tapping also has been tried. This is a method wherein 'a hole is lanced up through the lining material with an oxygen or powder lance; the bottom ofthe salamander is approached from its side or from beneath. Great danger is present in this very tricky operation due to the fact that gases in the furnace ten-d to force smoke, gas, llames and molten material lback towards the workers burning-in the hole. Furthermore, when the salamander is reached, it may start iiowing with ,an explosive force. When, however, this technique is used, the hot, i.e., molten, salamander is cast into prepared beds at the side of the furnace which requires careful `and considerable preparation. If inadequate beds have been prepared because of an underestimate of the quantity of hot metal to be handled, the molten metal overliows the beds and causes great idilliculty and expense in its final disposition. Consequently blast furnace operators who use the bottom-tapping practice would like to abandon it. Since, however, it has 4not always been possible to remove a salamander in molten state in the past, its rem-oval in a frozen state has heretofore been =a costly, dangerous, Iand time-consuming job.

Present procedure for removing a salamander requires that holes be drilled therein. This may be done with an oxygen `or powder lance, twist drill or star drill, an oper tion which alone may consume twenty-four .to fortyeight hours or more. In ldrilling the holes care is taken to see that they are drilled only about two-thirds through the mass in order to contain the force of the blast resulting `from the tiring of the explosive, such as dynamite,

'placed in the holes. lIt is well known, however, that often the 4holes are drilled entirely through the mass, especially in vthin sections, yand much trouble is thereby caused in shooting and break-up.

When a suicient num-ber of holes isV drilled, each hole ICC is packed with dynamite, Nitramon, or similar explosive, ltarnped Iand shot according to conventional blasting methods. Sometimes, using this technique, a blast may be good and a chunk of the salamander is broken olf. If la poor shot is obtained, the blast ries and shoots out of the hole and does no work. Repeated shots often bell out `and over-expand the shot hole to a point where it becomes useless. Cracks which develop tend to vent the force of conventional explosives with Ian eliect much the same as riding. For this reason it is often necessary to burn or drill new holes if the cracks do not extend far enough to actually llree the piece under attack. If a crack is large enough, it is sometimes stuffed with several sticks of dynamite which are then shot to try to force it open. It has been found that this procedure generally is ineffective, and it -is seldom used. Y

Using heretofore known methods, it has been found that it can take another five to seven or more days to shoot or blast an average salamander ranging from two hundred to tive hundred tons. Adding to this the time required to drill holes for blasting, the time required for yan average job is from seven to nine round-the-clock days. Larger Salamanders -require even more time.

In accordance with our invention the time required to break up and remove a rozen salamander is cut down markedly. Consequently great savings are eilected because Ia iurnace can be repaired, rebuilt or remodeled `and put back on line in only a fraction of the time required by heretofore known methods. In the practice of our invention the timeaconsuming task of burning or drilling holes in the mass is eliminated. 'I'liis novel result is taccomplished by the use oi shaped explosive charges 1ocated at selected positions on the surface of the salamander Iand then detonated. Due to our method of selectively shooting in holes in the `salamander and the subsequent working or chasing of cracks radiating out 'from the holes formed by the idetonation of the shaped :charges We have found that we can successfully break up and remove a two hundred to tive hund-red ton salamander in between twenty-four to forty-eight hours or the time required in the practice of heretofore known methods just in drilling holes.

`Our invention also insures a markedly increased safety Ifactorrin the practice thereof through the use of explosives with low heat and impact sensitivity.` Upon excessive heating explosives which we use normally will decompose and burn rather than Idetonate. Furthermore, such explosives, if by any chance they should become lost in rubble, would be very unlikely to explode even under the sharpest blows from machinery used in henidling the broken-up pieces of the mass, or for example, machinery used in cleaning out a furnace in which the salamander is being broken up. In fact, such explosives generally will not detonate from impact of a .3G caliber rie bullet. On the other hand, explosives normally used in heretofore known methods, such as dynamite, are both impact land heat sensitive. Many serious accidents have occurred when shots were lost ,and later hit, or just cooked off,-i.e., activated by heat.

-T he terms working or chasing cracks `as used herein mean placing `a selected, high velocity, detonating type explosive in a crack in such manner that it acts as a wedge so that when it is detonated, the crack [walls are forced apart vand the crack is opened up, lengthened, and deepened.

We have discovered that it is possible to initiate cracks in a hole and progressively expand Iand work these cracks throughout the entire extent of the @frozen mass. Liquid and/or plastic, and/ or free-flowing granular and/ or slurry types of explosives of the detonating type 'and of a viscosity such that they can be worked into the finest sacarse extremities of the cracks are used. Conventional explosives previously employed in blasting salamanders `are very difficult, if not impossible, to insert into small cracks, and `even if this can be done, will not detonate properly. ln accordance with our method, however, in working or chasing cracks the `selected explosive is placed deep in the cracks where it is wel-l confined and will, when detonated, deliver `a `maximum of energy per pound towards extending the crack, and breaking up the mass. :It will lbe apparent, therefore, that with our novel method, a much smaller quantity of explosive is required and the danger of blast damage is reduced. In the methods used heretofore huge charges of explosives were used in over* expanded shot holes in the hope of obtaining useful work from 1a small fraction of the energy released. Explosives :placed in cracks as described may be maintained therein in the desired position by `a tamp, suchpas mud, or other known material. Under some conditions water can be used. We have found that in order to work cracks properly, an explosive of sucient velocity must be used. An extraordinarily sharp and powerful detonation is most effective, when a charge is set off.

Our .ethod described above has made reference to a salamander in a blast furnace. It is also applicable to open hearth furnaces where the bottom must be removed periodically. ln this type of furnace the salamander has included fingers and masses of steel which often pose many problems in effecting the removal of the mass, and hence it is a time-consuming job. The bottom of a blast furnace is much thicker than that of an open hearth furnace and accordingly in the latter type of furnace the job usually can be accomplished faster. Nevertheless, down time is quite costly and may range from $15,000 to $20,060 and more per day for both blast furnaces and open hearth furnaces. It should be remembered that lost production is a vital matter insofar as profits are concerned and can, depending upon business conditions, be many times the down time costs.

lt is an object of our invention to provide a novel method for effecting the rapid break-up and removal of frozen metal-containing m-asses.

It is a lfurther object of the invention to provide a novel method .for effecting the rapid .break-up of frozen masses, such as salamanders in blast and open hearth furnaces, and eliminate time-consuming and dangerous operations heretofore considered necessary in this type of work.

The invention also consists in a novel method for removing frozen masses, such las frozen salamanders, in the selective use of 'high velocity explosive charges for forming holes in the salamander and the further use of high velocity explosive in increasing the size of such holes and widening cracks caused by the detonation of such explosive so that the rapid breakup of a given mass can be effected.

The invention is further characterized by the use of high velocity, explosive, shaped charges, selectively located on the surface of a mass to .be broken up which, when detonated, form deep holes therein and initiate cracks which can be widened through the use and detonation of high velocity explosive placed therein tand detonated such that in this manner a tough, huge, dense mass can rapidly be broken up `for removal from the space it occupied.

lt is a further object of the invention to provide a novel method for breaking up frozen masses wherein a given job can be accomplished in a minimum of time and with a maximum of safety to those who do the work.

The invention is also characterized by the provision of a novel method for breaking up salamanders in furnaces wherein a job can be accomplished in less down time of the furnace, with greater safety to those on the job doing the work, less danger to property, and at appreciably Ilower costs than with methods heretofore used.

lt is a further object of our invention to provide a novel method for rapidly breaking up frozen masses l wherein selected cracks in a mass `are worked or chased with high detonating types of explosives so as to pattern the break-up of the mass in a controlled manner and thereby effect break-up of the mass in a minimum of time and with a maximum of safety to life :and property.

With these and other objects not specifically mentioned in view, the invention consists in the novel features pointed out and described more in detail hereinafter, and set forth in the claims hereunto appended.

ln the accompanying drawings which form a part of this specification, yand in which like characters of reference indicate the same or like parts:

FGURE 1 is a diagrammatic sectional view of a salamander in a blast furnace with a shaped charge positioned on the surface of the salamander,

Ei'GURE 2 is a sectional view of a shaped explosive charge located on a mass to be broken up,

ElGURE 3 is a sectional view of a portion of the mass shown in EEGURES 1 and 2 after the charge has been detonated,

FEGURE 4 is a View taken on line 4 4 in FIGURE 3,

FEGURE 5 is a sectional view of the mass `in FIGURE 3 yafter an additional explosive charge has been detonated,

FIGURE 6 is a view taken on line 6-6 in FIGURE 5,

EGURE 7 is an enlarged view of the cracked mass shown in FIGURE 6,

FGURE 8 is a perspective showing the mass illustrated in `EEGURE 7 after a section has been broken away,

FIGURE 9 is a view somewhat similar to FIGURE 2 in which the shaped charge is enclosed, as with sand bags,

FIGURE l0 is a view showing a different type of shaped charge resting on a mass to be broken up,

EGURE ll is a sectional rview of a portion of the mass shown in FlGURE lt) after the charge has been detonated,

ElGURE l2 is a view on line lZ-lZ in FlGURE ll, and

FGURE URE 12.

Referring to the drawings, FIGURES 1 8 illustrate a preferred embodiment of our invention as applied to the breaking up of a frozen mass, :such as salamander 10, in blast furnace l2. ln FIGURE 1, furnace 12 is shown diagrammatically for purposes of illustration. It will be appreciated that in accordance with out invention it is possible to break up salamander l@ in a minimum of time, and without substantial damage to the furnace in which it is contained. In this way furnace l2 can be returned to production in only a fraction of the time required heretofore in the art.

When the job is started, salamander l@ is studied carefully in order to nd out if, in freezing, any cracks, lines, or zones of weakness have developed. If cracks are found, they are worked in the manner described herein, that is, the selected explosive is worked 4into the cracks and detonated. lf no cracks, lines or zones of weakness are found, the shaped charge 14 is placed at a selected position between the outer edge and center of the salamander and then detonated.

FIGURES 2 and l() show two known types of shaped charges which we have found give satisfactory results. Shaped charge ld comprises a core having an inner cone apex angle of approximately 60. This charge is provided with a cast or shaped conical lining 16, `such as cast or sheet copper, although other suitable metals such as steel or zinc can be used. The thickness of the lining sheet depends upon the size of the charge. The explosive ll constituting the charge is formed around the exterior of cone 16. In use, charge 114 is mounted on a stand-off 20, a selected distance above the target material, which, in the illustrated embodiment, is the surface of salamander lt?. This distance depends upon the size of the charge. We have found that with a charge having a base diameter of 31/2, a suitable stand-off height is from 6 to 9 inches, or a distance of approximately 2 to 3 diameters of cone 13 is a view taken on line ifi-i3 in FIG- 1-6. The same rule can be followed satisfactorily for all shaped charges referred to herein.

Shaped charge 114 shown in FIGURE 10 is of the socalled linear type. Except for its shape, its construction is generally the same as the so-called beehive type shown in FIGURES l and 2. Charge '1l-4 comprises an angular lining 116 of copper or other suitable sheet metal, such as zinc or steel, upon which is formed the explosive charge 118, as required in conformity to the size of the charge. Shaped explosive charges can be cast, molded, or handshaped in known manner. l

Assuming the distance between the lowaspaoed edges of charge 114 to be three inches, stand-olf 120 supports v the charge from 6 to 9 inches above the target material. Any suitable material, such as metal or wood rods, cardboard, or a sand support,.can be used for supporting shaped charges 14 and 114 above the target material. The angle of the apex of the cone in the Iso-called beehive type of charge r14, or in a cylindrical type of charge which is generally similar to charge v14 except that its outer Walls fonn the walls of Va cylinder, and the apex angle of a linear charge, such as charge 114, can be varied as desired. `In this connection reference is made to chapter 10, Principle-s of Shaped Charges, in The Science of High Explosives, written by Melvin A. Cook, and published by Reinhold Publishing Corporation, NewYork, New York (copyright 1958), for detailed information concerning the construction and characteristics of shaped charges, which per se do not form a part of our invention.

Referring again to IFIGURES 1 and 2, after shaped charge 14 has been placed at the-selected position on the surface of salamander 10, it is provided with a suitable conventional type of detonator designated 22, and detonated.

In accordance with our invention, high velocity, detonating type explosive is used exclusively. We have found that a detlagrating explosive will not give satisfactory results. Therefore, we employ high explosives of the detonating type which when detonated, generate gaseous products of decomposition capable of attaining extremely high pressures. This is especially the case when such explosives are used as shaped charges where the gases resulting from detonation of the explosives and volatiZ-ation of the liner are controlled and directed against a dense, tough, metal-containing mass, such as a frozen salamander.

Many detonating type explosives are available and perform satisfactorily. Examples of these are TNT, RDX, DBA4,.5, and 6, C-3 which has an RDX base, pentolite, a mixture of PETN and TNT, tetryl, Aerex, and Composition B. We have used successfully detonating explosives in which the velocities of the detonation wave `range was between 19,500 ftr/sec. and 25,000 ft./ sec. or more, and prefer to use those having the higher velocities. With explosives having this range of detonation wave velocities, the velocities of the jets directed against the ltarget material are higher, and, in practical use, range between 1.0D and 1.5D, where D represents the velocity of the detonation wave. Accordingly, the velocity of the jet striking the target surface is extremely high.

The apex angle ofthe cone of a shaped charge may vary from 40 to 80. The smaller the cone angle, the deeper in the penetrationbecause the velocity of the jet is higher. As this angle approaches zero, the velocity of the jet approaches a theoretical maximum of 2D.

As shown in FIGURE 2, a suitable initiating charge or detonator 22 is placed directly above the apex of shaped charge 14 and fired in known manner. A detonator such as an Ireco 3C Procord booster, manufactured and sold by Intermountain Research and Engineering Company, Salt Lake City, Utah, is one type of detonator which operates satisfactorily in initiating the detonation of charge 14. A detonator known as an engineers special cap, and a #8 electric cap are other examples ofcaps that will give satisfactory results. As the detonation wave proceeds down the vertical axis of charge 14, cone .16 collapses, and a jet of vaporized copper is squeezed out of the core of collapsed cone material 16 and directed down the axis of the charge as indicated by arrow A in FIGURE 2. The vaporized metal from cone 16 is the main penetrating agent of the jet. A shaped charge without a lining produces only an insignificant hole and hence gives unsatisfactory results. When charge 14 is formed of an explosive such as C-3 which has an RDX base, the velocity of this jet at its point of impact with the target material, salamander 10, is over 30,000 ft./sec., and the pressure is on the order of 250,000 to 300,000 atmospheres.

Referring to FIGURES Il and 3, the result of the detonation is the formation of hole 24 in salamander 10 which, when a 1.5 pound shaped charge is used, will penetrate about 18 inches or more downwardly into the mass where the admixed metal is cast iron. Where a similar type of shaped charge 14 is used in breaking up a salamander in an open hearth furnace in which the included metal is mainly steel, the depth of penetration of the jet may be somewhat less. Larger shaped charges will give greater penetration.

It has been found that usually the detonation of a single shaped charge 14 at a given selected position on salamander 10 is suiiicient to start a satisfactory break-up operation. It should be noted, however, that the diaml eter of an average blast furnace is between twenty-seven and thirty feet. Therefore, in the interest of expediting the break-up of a salamander, it may be desirable to use a plurality of shots at different selected points on the salamander, and then work the cracks formed in the manner described herein.

A single charge v14 may suliice to effect the necessary initial penetration in a section of a salamander so that the further steps of our method may be practiced. However, occasionally it is desirable to detonate a second shaped charge in the same location in order to obtain deeper penetration. When a second shaped charge i4 is detonated over a hole formed by the detonation of the rst charge, it is first carefully centered, i.e., over hole 24 (FIGURE 3), in order that the resulting jet as described above may extend the initially formed hole deeper, and desirably cause additional cracks and lines of Weakness to form in the mass.

The results illustrated in FIGURES 5 and 6 are obtained by placing a quantity of a selected, high detonating type explosive in hole 24 formed by the detonation of shaped charge 14 (FIGURES 3 and 4). The particular explosive may be the same type as used in shaped charge le but can be varied as :desired provided that it has a high velocity as indicated hereinabove. The explosives which are used are plastic, gelatinous, granular or fluid in state. They can be molded, pressed or poured into hole 24 (FIGURE 3) with the explosive extending into the bottom-most part of the hole and then tamped with a suitable material such as clay, sharp sand, mud or, in some cases, water. The explosive is then detonated in known manner using primacord, or a suitable cap or detonator to form'bulge 30 and cracks 218, as indicated in FIGURES 5 and 6. Fluid types of detonating high explosives, such as Aerex, made and sold by Aerojet- General Corporation, Downey, California, can be used with success.

If inspection of a -mass to be broken up shows that there are cracks extending downwardly into the interior thereof, it may be unnecessary to resort to an initial .penetration of the mass by use of a shaped charge in order to start the break-up of the mass. In this case, the cracks, such as cracks 28, shown in FIGURES 6, 7 and 8, are worked progressively by filling them with the required amount of a selected detonating type of high explosive, tamping the charge in place and then detonating the charges. With larger and wider cracks, plastic, gelatinous, or lgranular explosives can be used quite aromas readily, although lluid types can also be used. In the smalier cracks where it may be ditlicult to use plastic, granular or gelatinous types of explosives, lluid types can be used with great effectiveness since they ilow into the cracks. The working of the cracks is continued until parts of the mass are broken from the main or parent mass. lt will be appreciated that by a Selective working ot cracks 2S, it is possible to exercise a control over the breakup pattern of a mass. This technique is illustrated by a reference to FlGURES 7 and 8 wherein by selective placement of explosive in certain of the cracks, as for example, the two lower cracks 2S shown containing explosive, it is possible to cause the controlled separation of a wedgeshaped segment 33 as shown in FlGURE 8. In the same manner in breaking up any mass we can, by selective and continued working o cracks, control the rapid breaking up of a mass, thereby providing a pattern system which is highly advantageous in the practice of our invention.

FGURES 7 and 8 show the manner in which the breakup of salamander l@ progresses from the state shown in FGURES 5 and 6. In FIGURE 7, the selected high explosive 32, such as C3, has already been placed in the two lower cracks 2S and tamped, ready for detonation. Explosive 32 has not yet been placed in the two upper cracks 28 or in central opening 3i). The desired quantity of hiffh explosive is worked into cracks 2S, or it may in some cases be poured therein, as when Aerex is used, after which a tamp such as mud or clay is used to maintain it in proper place ready for detonation.

FIGURE 8 shows the results of the repeated detonatating or shooting the prepared section of salamander 1t) as discussed hereinabove. The break-up job has progressed to such an extent that a large chunk has been broken away, and fractures and lines of weakness have been developed through the mass and to the point that with additional development of cracks and lines of weakness 7.3 and by working, ie., placing charges of high explosive therein in the manner described and detonating them, the entire mass will be broken up into chunks and pieces which can be removed `from furnace l2 in a minimum of time. lt will be appreciated that the term deeloping as applied to cracks and lines of weakness means the repetitions detonation of char-ges of high explosive placed therein in such quant-ity and of such a nature that as the result of such detonation, the cracks and lines of weakness are widened and extended, so that the entire mass is broken up into fragments and chunks of a size which can be handled and removed from the furnace, vessel or site where located.

As noted hereinabove, the section of salamander 16 shown in FEGURES 3-8 is but a portion of the whole. The invention, however, contemplates a plurality of operations being carried out over the entire mass concurrently or in succession so that a break-up job can be accomplished as rapidly as possible. This will, however, depend upon the condition of mass to be broken up, and its location. i

FiGUlT-.E 9 iliustrates a slight modification in the invention as applied to the process disclosed in FlGURES l-S. in the ligure, shaped charge 214 is enclosed by sand bags 2id. Sand bags 216 perform the function of partially absorbing and reducing the air blast due to detonation of charge 2.14, rather than to conne the explosion. This use of sand bags or other enclosing means may be desirable in cases where the char-ges are being detonated close to the walls of a furnace so that only some ot the charges may be so enclosed before detonation.

FIGURES 10-13 illustrate a modied form of the invention in which a linear shaped charge is used. As shown in FIGURE 1t), charge M4 is positioned on the surface of a frozen mass, such as salamander lll, in the same general manner as in the case of charge if. Under some `operating conditions, it has been found desirable to form a wedge-shaped opening in the surface t5 of the mass, as when there is an overhang on a salamander along the edge. in a particular job, beehive or cylindrical shaped charges, and also shaped charges of linear and other configurations may be used, or only one or the other type charge may be used. As shown in FGURES ll and 13, the detonation of charge iid results Ain the formation of a deep wedge-shaped hole 12.4, having a relatively wide opening 126 (FGURE l2). The high explosives used in charges 3%; `and their characteristics on detonation vare the same as in the case of the charges i4 shown in FIGURES 1 and 2. Upon being detonated, the jet formed moves downwardly as shown by arrows AA to impact the surface of salamander 1i FIGURE 13 shows wedge-shaped opening 124 packed with a suitable plastic form of high detonating explosive, tamping being omitted. The explosive E26 is detonated in known manner by primacord, electric cap, or booster initiator 1.22 similar to initiator 22 described hereinabove. ri`he lines of force exerted by the detonation of explosive i2@ are indicated by arrows ist) and also are at right angles, to the plane of the paper so that not only are cracks and lines of Weakness formed but also wedgeshaped hole E24 is deepened and widened or expanded as the result of each shot.

Although specic references are made to masses such as salamanders, it is often desir-able to remove scabs or agglomerated burden material which has adhered to the side walls of a furnace, generally in the stack. This scab becomes a solid mass restricting the ow of materials within the furnace as well as reducing the effective furnace volume. This mass is a sever hindrance in cleaning out a furnace and must be removed before a furnace can be relined o-r repaired. As in the method applied in rthe removal of a salamander, we work cracks if they ere present `in the scaib by pressing, molding, or pouring explosive of the type described, into such cracks, and detonating them. lf no cracks are present when scab removal is begun, we fasten a small shaped charge on a selected spot in the scab and then proceed as described in ythe use of shaped charges.

it will be apparent from the above description and the disclosures in the drawing-s that we have provided a novel method for rapidly breaking up frozen and dense masses, such as salamanders, `in blast furnaces and open hearth furnaces. While reference is made to two types of metal handling furnaces, the method is not to be considered to be so limited since it can be employed for use in breaking up other kinds of frozen masses, especially those containing metal. The practice of our method involves the substantially instantaneous formation of deep penetrations or deeply extending holes in the masses attacked, after which by successive and progressive enlarging of the holes and cracks and lines of weakness emanating therefrom by detonating explosives placed therein, huge masses such as described can be broken up up in a minimum of time for removal as desired.

The quantity `of explosive used depends upon the size and depth of holes, such as 24 and 26, and the length, width, and depth of cracks, such las 28. Due to the manner in which we introduce selected explosives into these openings in the mass, and especially into the tip of a hole and the farthest extremities of cracks where they will deliver maximum effective energy per pound towards expanding and deepening such holes and cracks leading to the break-up of the mass, it is not necessary to completely lill the cavities being worked. Satisfactory results are obtained when holes and cracks are filled to between one-quarter and one-half their depth, although on occasion it may be desirable to use more explosive. The quantities given are, therefore, illustrative but not controlling.

Experience shows that smaller charges yand more eilicient placement lof explosives gives greater control and minimizes danger of blast damage to surrounding struc- 9 tures. Funthermore, the need for using large bulk charges in overexpanded shot holes is eliminated. It will be appreciated that when a large `section of a mass is broken away from lthe parent mass, it in turn can be reduced to fragments by the technique disclosed.

While reference is m-ade to the u-se of explosives in expanding and deepening holes, and in working cracks, it is to be understood that more than one type of exploysive can be used 4at the same time. It is quite possible to use one type of explosive in the initial formation of holes as by shaped charges 14 and 114i, and for deepening and expanding such holes in the manner shown in FIGURES 3-8 and 11-13, and to use another type or types in working cracks 28. In any event when a group of charges in a hole or selected holes and in cracks or selected cracks is lto be detonated, each charge is provided with a detonating element, which may be a cap or primacord. These are all connected together so that when one charge is red, all `are detonated.

We claim:

1. The method ot' breaking up a tough, dense metal containing mass comprising, placing a shaped charge of high Idetonating explosive at a selected position on the surface of fthe mass, detonating said charge to cause said charge to form a deep hole in said mass, repeatedly filling said hole with a quantity of a high detonating type explosive and detonating each such quantity of said explosive to enlarge said hole and form cracks and lines of weakness, placing a high explosive of the detonating type in said cracks and lines of weakness and detonating n said last-named explosive to expand and deepen the same and thereby effect the break-up of said mass.

2. The method defined in claim 1 wherein said shaped charge comprises an explosive charge with a lined cavity.

3. The invention rdeiined in claim 1 wherein said shaped charge is a beehive shaped charge.

4. The method defined in claim 1 including the step of locating a second shaped charge on the surface of said mass above and centered with reference to said deep hole, and then detonating said second shaped charge to further deepen said hole and initiate additional cracks and lines of weakness in said mass radiating outwardly from said hole.

5. 'The method dened in claim 1 wherein the detonation of said shaped charge produces a jet of fine-ly divided metal having a velocity of from approximately 19,500 ft./sec. and upward, said jet being operative to penetrate said mass and lform said hole and produce cracks and lines of weakness emanating from said hole.

6. The method of breaking up frozen metal containing masses comprising, directing a jet of vaporized metal of high velocity ata selected point of impact in a selected zone of said mass to form a deeply penetrating hole in said mass, placing a selected quantity of detonating type of high explosive in said hole and detonating said explosive to expand said hole radi-ally and axially, and form cracks radiating outwardly from said hole, again placing a selected quantity of said explosive in said hole and in said cracks and detonating said explosive to further enlarge said hole radially and axially and to widen and extend said cracks, and continuing the application of explosive to said hole and said cracks and detonating said explosive until said mass in said zone of said mass is broken up.

7, The method defined in claim 6 including the step of directing at least one additional jet of vaporized metal under high pressure into said hole made by said first jet to deepen said hole.

8. The method of breaking up a salamander in a furnace comprising, directing jets of vaporized meta-l of high velocity resulting from the detonation of metal lined shaped charges formed from high velocity detonating types of `explosives at selected points of impact on said smamander to form deep holes and cracks and lines of weakness in said salamander, and progressively and selectively placing char-ges of a detonating type of high explosive in said holes and said cracks and detonating said charges to deepen and expand said holes and widen, deepen and extend said cracks and lines of Weakness to eicot the break-up of said salamander.

9. The method of breaking up a salamander for removal from a furnace comprising, placing a shaped charge of a detonating high explosive having a metal liner on a support a predetermined distance above a selected location on the surface of a section of said salamander, detonating said charge and Aforming thereby a vaporized jet of metal directed at a very high velocity yto a point of impact on said surface of said section of said salamander, said jet forming a deep hole extending downwardly into said salamander, placing a charge of a detonating type of high explosive in said holes, securing said charge in said hole and then exploding said charge to widen and deepen said hole and to form cracks in said salamander radiating outwardly from said hole, placing another charge of said selected explosive in said hole and securing it in position therein and also placing quantities of said explosive in said cracks, detonating said explosive to further deepen and widen said hole and to expand said cracks, and continuing the placement of successive additional charges of said explosive in said hole and cracks until said section of said salamander is broken up and separated from the main mass thereof.

10.- The invention defined in claim 9 including the step of enclosing said shaped charge with protective means to partially absorb and reduce the blast due to the detonation of said charge.

lll. 'Ih-e invention defined in claim 9 wherein said explosive produces a penetrating jet having a velocity ranglng between 19,500 it/sec. and 40,000 ft./sec.

12. The method delined in claim 9 wherein a linear type shaped charge is used to provide an elongated jet forming ya wedge-shaped hole in said salamander.

13. The invention dened in claim 8 including the step of placing a selected explosive in selected cracks in said salamander to provide a detonating pattern, and after each detonation of the charges placed in said cracks, working and developing the same and other cracks to Yeiiect a controlled break-up of said salamander.

14. The invention defined in claim 9 wherein said shaped charge comprises a metallic liner, and wherein said explosive upon detonating produces a penetrating )et directed at a selected portion of said salamander with a velocity ranging from approximately 19,500 ft./sec. upwardly.

l5. The invention defined in claim 1 wherein said shaped charge of high velocity detonating explosive -includes a meta-l lined cavity, and wherein when said charge is detonating a jet of iinely divided metal is directed at said mass with Aa velocity of at least 19,500 ft./sec.

References Cited in the iile of this patent UNITED STATES PATENTS 1,927,059 Bahlke Sept. 19, 1933 2,301,855 Cliffe Nov. *10, 1942 A2,605,703 Lawson Aug. 5, 1952 `2,752,272 Fay June 26, 1956 2,839,435 Boswell June 17, 1958 

1. THE METHOD OF BREAKING UP A TOUGH, DENSE METAL CONTAINING MASS COMPRISING, PLACING A SHAPED CHARGE OF HIGH DDETONATING EXPLOSIVE AT A SELECTED POSITION ON THE SURFACE OF THE MASS, DETONATING SAID CHARGE TO CAUSE SAID CHARGE TO FORM A DEEP HOLE IN SAID MASS, REPEATEDLY FILLING SAID HOLE WITH A QUANTITY OF A HIGH DETONATING TYPE EXPLOSIVE AND DETONATING EACH SUCH QUANTITY OF SAID EXPLOSIVE TO ENLARGE SAID HOLE AND FORM CRACKS AND LINES OF WEAKNESS, PLACING A HIGH EXPOLSIVE OF THE DETONATING TYPE IN SAID CRACKS AND LINES OF WEAKNESS AND DETONATING SAID LAST-NAMED EXPLOSIVE TO EXPAND AND DEEPEN THE SAME AND THEREBY EFFECT THE BREAK-UP OF SAID MASS. 